The invention relates to a pivot joint with a bellows seal, in particular for use on automobiles. At a second bellows end of this bellows seal, the sealing of the bellows interior relative to the atmosphere is reinforced, in addition to radial sealing of the annular flange of the bellows relative to the pivot, by means of nonpositive and positive axial bearing contact against a part which is fixedly connected to the pivot outside the bellows.
In a pivot joint of this type, known per se from practice and from German Patent document DE 44 13 664 A1, the invention is concerned with the problem of improving the sealing effect at the second bellows end of the bellows seal.
The problem according to the invention is solved by a pivot joint for automobiles having a bellows surrounding the joint to form a bellows seal. The pivot joint includes a pivot housing, a first end of the bellows connected fixedly and leaktightly to the pivot housing, a pivot, and a second end of the bellows annularly surrounding the pivot leaktightly, wherein relative movements are possible between the second bellows end and the pivot. In the second bellows end, having a sealing effect, a radially outer annular contraction forms an annular flange terminating freely on an end face. A ring assists a radial sealing of the second bellows end and lies in the contraction. The second bellows end bears radially against the pivot via an approximately cylindrical sealing face which is provided with annular axially alternating elevations and depressions having a labyrinth-like effect. The elevations of the approximately cylindrical sealing face of the second bellows end in each case terminate axially in a last elevation which is designed as an annular collar with a cylindrical inner face. Defined by the features which are present in the bellows seal in an uninstalled state: (1) the end face of the annular flange is divided into an inner and an outer concave annular face, of which the outer annular face is designed with greater concavity than the inner annular face; (2) the angles of inclination of the annular faces relative to a bellows axis are approximately xcex1=70xc2x0 for the outer annular face and approximately xcex2=80xc2x0 for the inner annular face; (3) the radial extent of the outer annular face is approximately 12% in relation to the radius of the outer annular face of the annular flange of the second bellows end; (4) an annular depression is located between the annular collar, adjacent to the inner annular face, on the inner sealing surface of the second bellows end and this inner annular face; (5) flanks of the annular flange of the second bellows end run approximately parallel to one another; (6) the height of the annular flange in the region of the outer annular face measures uniformly approximately 8% of the outer diameter of the annular flange; (7) the ring is designed to be closed and made of inelastic material and projects radially outward into an annular region which is formed by the outer sealing face and in which said ring bears axially against the annular flange; and (8) the axial height of the contraction is smaller than the amount by which the ring would bear positively in this contraction, without the latter being widened, so that, with the ring inserted, this contraction is widened as a result of the elastic deformation of the material of the bellows forming this contraction.
By virtue of the measures according to the invention, both radial sealing and axial sealing at the second bellows end are improved considerably. Expedient refinements of the invention are described herein.
The leaktightness attainable according to the invention is not achieved in bellows seals of a similar generic type, such as, for example, according to German Patent document DE-U 18 75 318 and U.S. Pat. No. 3,378,286 or in the bellows seal according to German Patent document DE 44 13 664 A1. This is attributable to the fact that, in these known seals, the configuration and design of the sealing regions performing the actual sealing function are not optimally coordinated with one another.